This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ACTG 219 The purpose of this study is to collect and study clinical and laboratory information about you and your medical care in order to increase our knowledge of the best care for HIV-infected pregnant women and their children. The study will look at how good different medications are in lowering the chance that a baby born to an HIV-infected mother will get HIV.The study will also look at how different medicines work to lower the amount of virus in the blood or increase the blood cells that help the body fight infection.